Sucker rod jerk absorber



B. H. STEVENS SUCKER ROD JERK ABSORBER Inventor Filed Nov. 30, 1937Attorneys April 11, 1939.

Patented Apr. 11, 1939 UNITED STATES PATENT oFFlcE 1 Claim.

jerk to which the sucker rod is subjected during the well-pumping motionor operation.

In accordance with the present invention, a device is provided which isdesigned for interposition between two sections of a sucker rod for thepurpose of relieving the rod of undue vibration, torsional strain, twistand jerk; and the invention together with its objects and advantageswill be best understood from a study of the following description takenin connection with the accompanying drawing wherein:

Figure 1 is a longitudinal sectional view through the device withcertain parts shown in elevation,

Figure 2 is a transverse sectional view taken substantially on the line2-2 of Figure 1, and

Figure 3 is a perspective View of a piston.

Referring to the drawing by reference numerals it will be seen that theabsorber comprisesran elongated cylinder or barrel 5 into the upper endof which is threaded a cylindrical plug 6, and into the lower end ofwhich is threaded a cylindrical plug or coupling element 'I.

The plug or element 'I is provided in the free end thereof with athreaded socket 8 for receiving the threaded end of a sucker rodsection.

The plug 6 is longitudinally bored and is also suitably formed toprovide a packing box 9 in which is seated a suitable packing Il) and agland II, packing Il) and gland II accommodating a piston rod I2 asshown.

The rod I2 at one end thereof is suitably provided in a manner (notshown) to attach said' end of the rod to one end of a second sucker rodsection whereby the absorber may be interposed between the said sectionsof the sucker rod.

On the inner end of the piston rod I2 there is provided an elongatedpiston I3, one end of which bears against a washer I 4 held on the rodI2 between the lower end of the piston I3 and a nut I5 threaded on thelower or inner end of the rod I2 as shown in Figure 1.

Fitting snugly within the barrel 5 above the piston I3 is a cylindricalair chamber I6 formed of metal or other suitable material of hollowshell-like form and provided in its lower end with a circular series ofair ports I'I.

Between the chamber I6 and the piston I3 there is within the barrel 5 asuitable hydraulic fluid, I8, such as oil or the like.

Further the piston I3 ls suitably secured on the inner end of the rod I2through the medium of a conical wedge I9 which fits snugly within aconical bore 20 provided therefor in the piston I3, and at the base ofthe cone the wedge I9 abuts a shoulder 2l provided on the rod I2 asshown.

The operation, utility and advantages of a device of this character willbe apparent from the following:

The pumping action causes an upward pull on the piston rod I2 which,through piston I3, exerts pressure on the hydraulic fluid I 8. '1211s inturn results in pressure being exerted. on the air chamber I6 throughthe ports I'I so that the upward movement of the rod I2 is transmittedto the lower section of the sucker rod for causing the latter to moveupwardly with the rod string. Manifestly by providing the air chamber I5and the fluid IB within the barrel 5 above the piston I3 a cushioneifect is obtained with the result that no jerk or snap is imparted tothe sucker rod string during the pumping operation.

On the downstroke of the sucker rod string the pressure exerted on theair chamber I5 together with the partial vacuum created on the hydraulicfluid I8 by the downward motion of the piston rod I2 and piston I3causes the parts to return to their normal position.

It will thus be seen that I have provided a device which may be readilyinserted between two sections of a sucker rod string and which device ifso used will serve to absorb the shock or jerk to which the rod sectionsare ordinarily subjected during the pumping operation.

It is thought that a clear understanding of the construction, utilityand advantages of an invention of this character will be had Without amore detailed description.

Having thus describedthe invention what is claimed as new is:

A cushioning device for a sucker rod string comprising a barrelcontaining fluid, a coupling member closing the lower end of the barrel,a plug closing the upper end of the barrel, a piston rod passing throughthe plug, packing means in the plug through which the rod passes, apiston in the barrel connected with the lower end of the rod, an airchamber in the upper part of the barrel below the plug including acylinder having a working fit with the barrel, a tubular member in thecylinder and having a working fit on the rod, and end pieces connectedwith the tu bular member and the cylinder and forming an air chamberbetween the tubular member and the cylinder, the lower end piece havingperforations therein for adjoining the interior of the air chamber withthe interior of the barrel.

BEN HARWOOD STEVENS.

